Molding machine



Dec. 25, 1945 R c, TRA Y 2,391,527

MOLDING MACHINE Filed Feb. 11, 1943 4 Sheets-Sheet l gwuwwtom I IPC.7;;acy 4, M w/ g awn/wa Dec. 25, 1945. R e. TRACY 2,391,527

MOLDING MACHINE Filed Feb. 11, 1943 4 SheetsSheet 2 Dec. 25, 1945.

P. c. TRACY 2,391,527

MOLDING MACHINE Filed Feb. 11, 1943 4 Sheets-Shed 3 i l 1 3?: Md 1)} H]20: i

a4 e7 e8 Y C A R T C P MOLDING MACHINE Filed Feb. 11, 1943 4Sheets-Sheet 4 PLATEN CONTROL dwl'rcfl E 5 R E V E R m T m P F002 WAYSOLENOID VA we v a w tom ,Z; .49 P (1.7520167 Wangsure caps and variousother threaded articles.

Patented Dec. 25, 1945- 2,391,527

- UNITED STATES PATENT OFFICE MOLDING MACHINE I Parker C. Tracy, Toledo,Ohio, assignor to Owens- Illinois Glass Company,- a corporation of OhioApplication February 11, 1943, Serial No. 475,470

' 14 Claims. ('01. 18- 16) My invention relates to machines for moldingan injection moldin m c ne or mold n articles formed with screw threads,including 010- ternally threaded articles, comprising separable platesor supports in one of which are mounted molding plugs with spiralmolding surfaces, and in the other of which are mounted the cooperatingmold sections, and means for separating said plates after the moldingoperation, leaving the molded articles supported on the moldin plugs,and means for thereafter removing the molded articles by rotation of theplugs.

Other objects of the invention will appear hereinaiter.

Referring to the accompanying drawings which illustrate a machineembodying the present in- These may be made of various materials,including organic plastics of both the thermoplastic and thethermosetting type.

An object of the invention is to provide a multiple type machine, whichis simple and reliable in operation, adapted for molding a considerablenumber or articles simultaneously.

In Patent No. 2,326,382, Motor control, granted August 10, 1943, toMoreland and Tracy, there is disclosed a machine ,of the type aboveindicated for making internally threaded closure caps and the like. Insaid machine the screw-threaded n i ni molding plugs, for molding thethreaded interior Fi '18 a partly dia rammatic elevation of the surfacesof the articles, are spirally advanced achine ating through suitabledriving mechanism and are Fig. 21s a plan view of the same. Fig. 3 is across sectional elevation of the maheld in molding osition by the motorwhile the c i e t ts en a ay.

latter is stationary under a reduced torque. After ig- 4 is a S n at e lne H on Fi 3.

into molding position by an electric motor operthe molded articles haveset or hardened, the motor is reversed to withdraw the screw-threadedmolding plugs.

The present invention embodies certain improvements over the disclosurein said patent,

an object of my invention being to provide means for holding the moldingplugs in operative position independently of the motor.

A further object of my invention is to provide a molding machine of thetype indicated in which the molding plug or element with its spiralmolding surface, may be withdrawn from the molded article by rotatingsaid element about its axis while the molded article is held againstrotation, and in which said rotative element is guided and itslengthwise movement during said withdrawal is controlled solely by thespiral surface 01' the molded article. The invention provides aconstruction in which the .molding plugs may be brought to moldingposition by a non-rotative, straight-line forward movement, andwithdrawn from the molded article by rotating the plugs while the moldedarticles guide them in a spiral path to a retracted position.

A further object of the invention is to provide a moldlng machinecomprising cooperating molding elements, one or which is provided with aspiral or screw-threaded molding surface, and providing automatic meansby which the mold sections are slightly separated after the moldedarticle has set. to relieve the pressure, and the threaded moldingelement thereafter withdrawn by a spiral movemen Fig. 5 is a section atthe line E- on Fig. 4. Fig. 6 is a fragmentary sectional elevationshowing a mold with the molded article therein and the screw plugpartially retracted.

Fig; 7 is a similar view showing the movable platen withdrawn.

Fig. 8 is an elevational view of a series of limit switches and theirmountings and the switch operating means.

Fig. 9 is a plan view of said switches.

Fig. 10 is a wiring diagram or the electrical equipment.

The invention as illustrated in the drawings is embodied in a machinewhich, except as to perm shown in detail in Figs. 3 to 9 inclusive, ismainly of prior art construction as disclosed for example in the patentto Moreland et al. No. 2,298,-= 716, October 13, 1942, Machine formolding thermoplastics.

Referring to Figs. 1 and 2, th machine frame ll includes vertical endmembers l2 and I3 and horizontal tie bars H. A stationary bolster platel5 has a fixed mounting on the bars H. A bolster plate to slidablymounted on said bars, is connected to and forms a part 01' areciprocating carriage by which the complementary sections of the diesor molds are moved to and irom each other. The carriage is reciprocatedby a hydraulic motor I! having operating connections therewith throughmechanism including toggles 18. The hollow molds or dies 20 (Fig. 4) aremounted in a die plate 2| to which is attached a backing plate 22, theplate 22 in turn being a further object or the invention is to providesecured to the stationary bolster plate is. The

rendered soft or plastic.

'33 formed in the face of ing and setting, by means carriage includes aplurality of vertically disposed, juxtaposed plates 23, 2t, 25, and 26.The

plate 2.3, which serves as a movable platen or die plate, has mountedtherein bushings 21 or die sections complemental to the dies '20,

Means for supplying molding material to the dies includes a hopper 28(Figs. 1 and 2) in which the material in powdered or granular form isplaced. The member l2 provides a heating chamber through which thematerial passes on its way to the molds and in which it is heated and Aninjection plunger reciprocated vertically by an and forces the plasticmolding 29 is periodically electric motor 30 material through aninjection nozzle and passageways to the mold cavities. The moldingmaterial is admitted in measured quantities from heating chamber under3| including a the hopper 25 to the the control of a feeder devicereciprocating feeder plug operatively connected to the motor 30. 4

Referring to Figs. 3 and 4, the passageways through which the moldingmaterial is forced into the mold cavities include a sprue opening 32extending through the plates 22 and 2! and communicating with branchsprues or passageways the plate 23 and opening into the mold cavities.Associated with each of the molds or dies is a screw plug 8% comprising.a head t l (Fig. 5) and body at having a screwthreaded connection. Thehead 3& is formed on thread 35 for moldits forward end with a screw ingthe thread on the inner face of the molded article at, herein referredto as a screw cap. The plugs 34%, hereinafter referred to as forceplugs, are mounted for movement in the direction of their length andalso for rotation about their axes, thus permitting them to be withdrawnfrom the molded caps. Rotary motion is transmitted to the plugs throughspur gears 31 individual backward rotation of the plugs is continued tocomplete the unscrewing or withdrawal from the ing all of the cam blocksup and down. When the camblocks 53 are moved upwardly, they force themolding plugs at forward to their operative position shown in Figs. 4and 5 and then serve as a positive means for holding the plugs in suchposition during the molding operation,

After the set of caps has been formed in the molds and the materialcooled and hardened, the cam blocks 53 are lowered as shown in Figs. 6

and 7. This permits the plugs to be rotated for.

partially unscrewing or withdrawing them from the molded caps 35,bringing the'plugs to the Fig. 6 position while the die plates 2|, 23are still together (Figs. 5 and 6). The carriage or movable platen isthen withdrawn (Fig. '7) and the molded ,caps. It will be noted that thecaps are held against rotation as they are all connected by the spruewhich forms in the sprue channel 33 (Fig. 3).

.The operation of the machine is under the automatic control ofelectro-responsive mecha-' nism including micro-switches which functionas limit switches. I'hese include among others,

- three limit switches (Figs. 8 and 9) designated the platen 23 andthereto, said gears being positioned in openings provided in the plate26 and backed by the plates 23 and 2% which hold the gears againstmovement in an axial direction. Each force plug 8% is formed withlongitudinal ribs or teeth 88 to provide a driving connection with thesaid gears.

Means for rotating the force plugs includes an electric motor as mountedon a platform at which in turn is mounted on the carriage. Drivingconnections between the motor and plugs include a train of gearingwithin a gear case 52 for driving a shaft st. The latter drives asprocket chain as trained to a shaft 65 journalled in Keyed to the shaftat is a pinion ill which meshes with a pair of spur gears t8 keyed toshafts t9 iournalled in the plates 23 and'ZS. Also keyed to the shafts59 are gears 59 each included in a gear train comprising gears blrunning in mesh with the gears 8'6. It will be noted that, as clearlyshown in Fig, 3, the gears are so arranged that all of the gears of withtheir plugs 36 are rotated simultaneously in the same direction. Themotor St is periodically plugs alternately in oppositely directions ashereinafter set forth.

reversed for rotating the over a sprocket gear id keyed the plates 23,2t.

L3, L5 and LB which are actuated by a contact block 66 having ascrew-threaded connection with a screw shaft 8| journalled in a frame 52mounted on the platform M. The shaft Si is driven from the motor tilthrough a sprocket chain (is trained over sprocket wheels. on the motorshaft and the shaft 8|. These three limit switches are slidably mountedfor individual.

adjustment lengthwise of the frame 82, by means of screw rods es.

A limit switch L5 (Fig. 4) is mounted behind is operated when the platenis "cracked open, as hereinafter set forth. A limit switch L5 (Fig. 4)is mounted and arranged to be closed by a contact arm 65 on the crossbar51 as the latter completes its downward movement by which the wedges 53are withdrawn. A limit switch L?! (Fig. 2) is actuated by a contact armas on the mold carriage as the latter nears the limit of its moldopening movement.

The several steps in the operation of the machine take place in thefollowing order. Assuming the mold carriage to be withdrawn and theforce plugs St in their retracted position, the hydraulic motor whichactuates the carriage, is started and moves the carriage forward andthereby closes the molds. The force plugs are at the same time rotatedby the motor 50 and injected into the molds and allowed to set andharden. The die plates are then cracked as a preliminary to theunscrewing or retraction of the force plugs.

This cracking consists in withdrawing the carriage a slight distance,sufiicient to relieve the pressure of the wedges 55 against the plugsbefore the backward rotation of the plugs commences. As the caps aremolded under a very high pressure, any attempt to rotate the plugsbefore such cracking operation might'place an undue strain on the moldedcaps causing twisting or'breakage. It would also tend to sever the capsfrom the sprue and thus interfere with their final removal from theplugs. It will be noted that the sprue links the caps together andpermits the entire roup to electrical controls.

place, the piston motor 58 operates to lower the wedges 55. As thismovement is completed, the motor 40 is started and rotates the plugs 34backward to an intermediate position (Fig. 6) in which they are partlyunscrewed from the mold caps. The motor 40 is then stopped and at thesame time the hydraulic motor is started and separates the die plates sothat the plugs 34 withdraw the molded caps from the 'molds 20.. As thismove-.- ment is about completed, the motor 40 is again started androtated backward to complete the withdrawal of the plugs 34 from themolded caps. The motor 40 is then automatically stopped, therebycompleting the cycle.

Referring to the electrical diagram (Fig. the force plug motor 40isconnected in a threephase system comprising main line wires a, b, c,which system also supplies current for the various To start the platenforward for closing the molds, a platen control switch III which may beoperated by hand, is actuated and establishes a circuit for a valvesolenoid II and thereby opens a valvefor the hydraulic motor I! whichthen operates to move the platen forward. This circuit may be tracedfrom the line wire a, through conductor 12, switch 10, its contact 10F,wire I4, platen forward relay I I, wire 15, to line wire b.

The above operation of switch 70 at the same closes a circuit through acontrol relaycoil 11 connected in parallel with the coil II. The coil I1being thus energized, moves the relay contact I8 to open position andcloses contact 18 to thereby complete a circuit for'the forward"solenoid F of a circuit closer 19. This circuit extends from line wire athrough wire 72, contact bar w limit switch L3, wire 8I, contact bar 82,coil F, to line wire b. Solenoid F being energized, closes switch 79 sothat the motor 40 is started and runs in a forward directionconcurrently with the forward movement of the platen. The force plugsare thus rotated in a forward direction and brought to molding positionwithin the dies 20.

As the plugs complete their forward movement, the contact block 60 (Fig.8) operates the limit switch L3 and thereby opens the the coil F whicheffects an opening of the motor switch 79 and stops the motor. Theinjection of molding material into the molds, molding and cooling orsetting of the molded caps, now takes place.

Following this, the platen control switch 10 is reversed, either by handor under the control 01' an automatic timer (not shown). circuit for aplaten reverse circuit extends from main a switch [0, contact and platenreverse solenoid 90, which through wire I2, 70R, wire 9|, contact bar 92solenoid 90. The solenoid 93 circuit through- This makes a" plugsindividual to now operates a valve for the hydraulic motor I? and startsit in the reverse direction for cracking the molds.

As soon as the slight distance,

platen has been withdrawn a it operates the limit switch L4 (Figs. 4 and10) This completes a circuit through a control relay R3. This circuitmay be traced from main a through wire 12, contact bar I8, wire 93,limit switches L6 and L6, wire 94, relay R3, and wire I5 to main b. Therelay R3 being thus energized, operates to make a circuit for a solenoid95 which valve which controls the piston motor 58. The latter thereforeoperates to withdraw the cam blocks 55. i

As the motor piston completes its downward movement (Fig. 4) the contactarm 65 operates then operates a four-way solenoid' the limit switch L5,moving it to closed position (Fig. 10). This completes a circuit for acontrol relay RI, which circuit may be followed from main a through wireI2, contact bar 18, wire 83, limit switches L8 and L5, relay RI and wire15 to main b. The solenoid RI being energized, moves its contacts 95 and81 to closed position. Contact 91 closes a circuit for a relay R6 andcauses it to open the contact 92 in circuit with the solenoid so thatthe platen motor is stopped. The contact 36 completes a circuit throughthe coil R controlling the reverse or backward movement of the motor 40by which the force plugs are unscrewed. This circuit may be traced frommain (1 through wires 12, 98, contact 96. wires 98, contact IIII, wireI02, solenoid R, wire 15 to line wire Solenoid R therefore operates itscircuit closer and starts the motor 40 in reverse direction for partlyunscrewing the screw. plugs from the molded caps.

When the screw plugs reach an intermediate position (Fig; 6) the contactblock 60 (Fig. 8) opens the limit switch L6. This opens the circuitthrough the relay RI which being de-energized, opens the contacts 96 and91. The contact 96 being in the control circuit for the motor 40, themotor is stopped. The opening of the contact 81 breaks the circuitthrough the relay R6, which is therefore deenergized and allows itscontact 82 to be closed. This completes the circuit for the platenreverse" solenoid 90 so that the platen is again started in its backwardor reverse direction. The molding plugs 34 with the molded articlesattached thereto, are thus withdrawn from the molds 20 as beforedescribed.

Before the platen completes its backward movement, it closes the limitswitch Ll (Figs. 2 and 10) This completes a control circuit through thecontrol solenoid R of the motor 40 for again starting the motor in abackward direction. Such circuit may be traced from main a through wire'22, limit switches L8, L1, wire 99, contact I0 I, solenoid R, wire 'I5to main b. This reverse operation of the motor completes the unscrewingof the mold plugs from the molded articles. The contact block 60 thenoperates to open the limit switch L8 (Fig. 8) thereby opening thecontrol circuit for the The platen is mold opening cycle.

Modifications may spirit and scope of I claim: a

1. An injection molding machine comprising a carriage, a train of gearsmounted thereon including a multiplicity of annular gears, molding saidannular gears and each extending through its said gear and having adrivalso stopped when it completes its movement, thereby completing a beresorted to within the the appended claims.

ing connection therewith for causing the plug to' rotate with the gearand permitting a straight lengthwise movement of the plug within itssaid gear while the gear is held stationary, said plugs being formedwith spiral molding surfaces, dies cooperating with the plugs formolding articles, means for moving the plugs lengthwise into moldingposition, means for holding the gears from rotating during saidlengthwise movement of the plugs, and means for driving said gear trainand thereby simultaneously rotating the molding plugs and causing themto be guided spirally by the molded articles to a retracted position andto be separated from the said articles.

2. The combination of a carriage. a molding plug mounted therein forrotation about an axis motor 40 and stopping the latter.

thereby forming a stop abutment by plug is held in said die plate andand for movement lengthwise of said d plug being formed with a helicalmolding ace,

means for moving said plug lengthwise to a mold ing position including astop block mounted in the carriage, and means for moving said block into1 accuser in the direction or said lengthwise move eat and therebyperiodically projecting the plugs into molding position, stop blocksindividual position behind the molding plug to hold it in said moldingposition.

3. Thecombination or a e, a molding plug mounted thereinfor rotationabout an and ior movement lengthwise oi said axis, said plug beingformed with a helical molding surface, on for moving said pluglengthwise to a molding position including a wedge block slidablymounted in the carriage,- said block in a direction terse tosaid axisand sliding it into a tion behind the molding stationary die plate andthere to the plugs and mounted on the carriage for reciprocatingmovementinto and out of an operative positionv in which they formabutments for the molding plugsand thereby hold them in moldingposition, a motor, means providing driv I'ing connections between themotor and said operative position, actuated by the movement of thecarriage d means for moving I blocks for moving the latter into and outof said and electro-responsive means .for controlling the operations ofsaid 'motor.

8. A molding machine comprising a carriage, a molding plug mountedtherein and formed with a spiral molding surface, a cooperating moldsection formed with a mold cavity into which the said plug projects,said plug being mounted for rotation about an axis and for lengthwisemovement inthe carriage in the direction of said axis, means forintroducing molding material into the mold, an electric motor, gearingforming drlving connections between the motor and said plug for rotatingthe latter, means for moving'the carriage, wedge blocks individual tosaid plugs versely of the plugs into and out oi position to term stopsfor the plugswhile the latter are in said molding position, a motor, andoperating connections between the motor and said blocks.

5. an injection molding machine comprising oppositely disposed verticalplates including a stationary die plate and-a movable plate, a carriageon which the movable plate is mounted, means for reciprocating thecarriage toward and from the die plate, molds each comprising a hollowmold section mounted in the die plate, and a molding plug mounted in thecarriage {or lengthwise and rotatlve movement therein, stop blocksindividual to the plugs and mounted in the carriage for movement in adirection trans= verse to the movement of the carriage for moving saidblocks into and out of stop -positions in which they iormabutment stopsfor said plugs, a piston motor, and means providing operatingconnections between the motor" and stop blocks.

6. An injection molding machine comprising astationary support, acarriage, molds each comprising a hollow mold section having astationary mounting in said support and a molding plug mounted forrotation and lengthwise movement in the carriage, means forreciprocating the car= rings in the direction oi'said lengthwise move-'ment and thereby periodically projecting the plugs into moldingposition, stop blocks individual to the plugs and mounted on thecarriage for re ciprocating movement into and out of an opera-.

tive position in which they form abutments for the molding plugs andthereby hold them in moldi g position, a motor, and means providingdriving connections between the motor andi said I blocks for moving thelatter into and out of said operative position.

' '7. An injection molding machine comprising 70 a stationary support, acarriage. molds each comprising a hollow mold section having astationary mounting in said support and a molding plug mounted forrotation and lengthwise movement 4 in the carriage, means forreciprocating the car and mounted in the carriage for movementtransplu'glengthwise relative to said mold section for withdrawing themolded article from said mold section, means for guiding the plug in astraight line and holding it against rotation during said lengthwisemovement. electro-responslve means controlling the operation of saidmotor and op= erative automatically to start the motor and cause aminimization of the plug in the carriage and Imolds', eachincluding ahollow mold section and.

a molding plug formed with a spiral molding surface, a stationarysupportin which said hollow sectionsare mounted, a carriage in which themolding plugs are mounted for lengthwise movement, means for moving thecarriage toward and said support,- means for moving the molding plugsrelative to'the carriage lengthwise into a molding position in whichthey protrude beyond the carriage into the hollow mold sections, meansfor injecting molding material into the molds, automatic carriagewithdrawing means for withdrawing the carriage a short distance andthereby cracking the molds, automatic plug rotating means for thencausing a combined rotation and lengthwise movement of the molding plugsrelative to the carriage and thereby partially withdrawingthem from themolded articles while the latter are within the hollow mold sections andthen stopping the plugs, said carriage withdrawing means being operableto then'withdraw the carriage and cause the moldedarticles to bewithdrawn from the hollow mold sections, said plug rotating means beingoperable thereafter to again rotate the-molding plugs and completelyseparate them from the molded articles, and aufrom tomatic timing andcontrolling mechanism for initiating, controlling and synchronizingsaidstraight-line, non-rotative movement relative to and from said dieplate, a die plate mounted on its support toward and from the other die,means the carriage and movable therewith to bring the molded by saiddies. ing plug mounted in the carriage and said mov- I 11. An injectionmolding machine comprising able die plate and formed with a spiralmolding oppositely disposed die plates, means for relasurface, means formoving the molding plugs tively moving said plates to and from eachother, lengthwise relative to said movable die plate into relative tothe other die plate, means for moving are together, means providing asprue channel Jecting a molding material into said hollow die. s h nd te pa ly w t d wi the threading it from the molded article, means foropen, said plus rotatin means e n p a l t mechanism for controlling andsynchronizing said fecting and Controlling said operations of themovements of the die plates and molding plug. plug rotating means.

12. A molding machine comprising a pair of 14. An injection moldingmachin comprising die plates relatively movable toward and from a St i ny i Pl a ria e movable toward plug mounted in one of said plates andformed hollow mold section mounted in said die plate and said plug beingmounted for rotation about its x s xt ndin in t direction f m v m nt ofing the plug while said di plates m t cavities, means for injectingmolding material movement in the direction of said axis and thereawayfrom the Stationary die Pl W il th being operable to rotat th l after tmolded operative to rotate them simultaneously, and au- 13. An injectionmolding machine comprising articles from said 911188- a stationary dieplate, a carriage movable toward R ER C A

